An increasingly important requirement of adhesives is that they not only have good adhesive properties, but that they are also biodegradable. The common adhesives, however, do not meet this requirement and strong adhesives are generally not at all biodegradable, or only to a small extent.
A number of biodegradable pollers are know including poly(lactic acid), poly(glycolic acid), poly(hydroxybutyrate) and the like. These pollers are degradable in aqueous environments. They are used for medical applications, such as implants, medicine and surgical materials. However, they are not suitable for adhesives or glues. At best they can serve as binders in aqueous solutions for certain applications.
Mixtures of natural pollers and synthetic pollers are known which can be used as biodegradable compositions, such as starch in combination with nylon, polyropylene, or polystyrene. Also known are combinations of gelatin and resorcinol-formaldehyde resin, which are biodegradable.
In addition, pollers are known which in aqueous solution can serve as adhesives and which are biodegradable as well. Examples of these are poly(vinyl alcohol), poly(ethylene oxide), poly(vinyl pyrrolidone) and the like. These pollers can, however, only be used in aqueous environment and have only a limited range of applications. Also known are derivatives of natural products which are biodegradable and have adhesive properties, such as carboxymethyl cellulose, amylose from starch, and casein from milk.
Biodegradable adhesives made from these known products either have adhesive properties which are insufficient or applications which are limited.